Free Peptide Calculator
Enter the milligrams on the vial, the bacteriostatic water you added, and the amount you want to measure, and PepCalc shows the concentration and the mark on a U-100 syringe while also solving the water volume for a mark you choose.
Blends
Optional. Extra peptides are added to the vial total.
Waiting on Input
5 mg vial, 2 mL water, 250 mcg. Example only, not a dose.
History
On this browser only.
0 logged
Press Log to keep a result here.
How to use PepCalc
- Choose Dose to units, or Units to water if you already know the syringe mark you want.
- Enter the peptide milligrams on the vial and the milliliters of water you added.
- Enter the amount you want to measure, in mcg or mg. PepCalc converts 1 mg to 1,000 mcg before it divides.
- Pick the syringe barrel (100, 50, or 30 units). Add dead space only if you want that extra volume included.
- Read the concentration and the unit mark. Copy the result, or save the row in History on this browser.
Why use PepCalc
Syringe marks are volume, not milligrams, and PepCalc does that conversion in the browser, covering dose to units, units back to water volume, blends of up to three peptides, optional dead space, and a syringe scale you can drag, while history stays on this device because there is no account and the calculator does not choose an amount for you.
Use cases for PepCalc
- Turn a vial strength and a water volume into mg/mL and a U-100 mark.
- Solve how many milliliters of water land a chosen dose on a chosen unit mark.
- Add two or three peptides in one vial and use the combined milligrams.
- Check whether a draw fits a 30, 50, or 100 unit barrel.
- Convert mcg and mg, then reopen the same numbers from History on this browser.
Reconstitution and dose math
Reconstitution here means a measured volume of bacteriostatic water was added to a dry vial, after which the powder and the liquid are one mixture and every mark on the syringe is a fraction of that mixture.
Concentration is vial milligrams divided by water milliliters, draw volume is the amount you typed divided by that concentration, and on a U-100 syringe units are milliliters times 100, so a 5 mg vial in 2 mL is 2.5 mg/mL and measuring 250 mcg from that mix is 0.1 mL, or 10 units, which is an example rather than a dose.
The other direction solves for water, so you name the vial strength, the amount you want to measure, and the unit mark you want to land on, and the calculator returns the milliliters that put that amount on that mark.
By James Li, Lead Editor · Updated
FAQ
Getting started
How do I use a peptide calculator?
Enter the milligrams on the vial, the milliliters of bacteriostatic water you added, and the dose in mcg or mg. PepCalc shows the concentration, the volume to draw, and the mark on a U-100 syringe. Presets (5 mg, 2 mL, 250 mcg) are only shortcuts.
What is a peptide calculator?
It converts vial strength and water volume into a syringe mark. The numbers on an insulin syringe are volume, not milligrams.
Can I enter the dose in mg?
Yes. Switch the dose unit between mcg and mg. One milligram is 1,000 micrograms, and PepCalc converts before it divides.
Does it work on a phone?
Yes. The inputs, presets, and syringe scale are sized for a phone. The FAQ is on the same page.
The math
How does it turn milligrams into syringe units?
Divide vial milligrams by water milliliters to get the concentration. Divide the amount you want to measure by that concentration to get milliliters. Multiply milliliters by 100 for a U-100 mark, because one unit is 0.01 mL.
How many doses are in the vial, and how long will it last?
Doses are total peptide in micrograms divided by the dose, rounded down. A 5 mg vial at 250 mcg is 20 doses. How long that lasts depends on how often you draw. Storage is separate: many reconstituted vials are refrigerated and used within about 28 days. Follow the guidance that came with the product.
Is the result exact?
The formula is exact for the numbers you type. It does not fix a misread label, an incomplete mix, or liquid left in the needle unless you set dead space.
What is the difference between a dosage calculator and a reconstitution calculator?
Usually none. Reconstitution asks how much water to add. Dosage asks how many units to draw afterward. PepCalc does both: Dose → Units, and Units → Water.
BAC water
How much BAC water should I add?
There is no single volume. More water lowers concentration and spreads a small dose across more marks, which is easier to read. Switch to Units → Water, enter the vial amount, the dose, and the unit mark you want. PepCalc solves for the milliliters.
How much water for a 10 mg vial?
10 mg in 2 mL is 5 mg/mL. At that strength, 250 mcg is 5 units and 500 mcg is 10 units. Three to five milliliters makes smaller doses easier to measure. Enter your own numbers for the exact mark.
How do I mix a peptide?
Wipe both stoppers, draw the calculated water, inject it slowly down the inside wall of the vial, and swirl until the powder is gone. Do not shake. Then refrigerate.
What does reconstitution mean?
Dissolving the dry peptide in a measured volume of bacteriostatic water so each milliliter, and each syringe unit, contains a known amount.
Specific peptides
How do I calculate BPC-157?
Enter the milligrams on the vial, the water you added, and the dose you intend to measure. PepCalc does not choose a BPC-157 amount.
How do I calculate a BPC-157 and TB-500 blend?
Add each peptide under Blends with its own milligram amount. Concentration uses the combined total. Confirm the ratio with whoever prepared the vial.
Do ipamorelin, tesamorelin, semaglutide, retatrutide, sermorelin, and TB-500 use different math?
No. Any milligram-labeled vial uses the same three steps. Enter the strength on that vial and the dose you are measuring. Do not copy a dose from a different product.
How do I reconstitute tirzepatide?
If the product is a dry vial you mix yourself, use either mode. Pens and premixed devices are already liquid. Do not read their click marks as if you reconstituted a dry vial unless the label says you did.
What about PT-141, AOD 9604, or a 10 mg MOTS-c vial?
A 10 mg vial plus 2 mL of water is 5 mg/mL, so 1 mg is 0.2 mL (20 units) and 5 mg is 1 mL (100 units). These figures are arithmetic, not dose advice.
Where is the dosing chart?
The live result replaces a static chart. A printed chart is wrong as soon as the water volume changes.
PepCalc
What is PepCalc?
A free peptide reconstitution calculator in the browser. It does dose-to-units, units-to-water, blends of up to three peptides, optional dead space, and a link that reloads the same numbers. No account.
How does PepCalc compare with other peptide calculators?
It covers reverse water math, blends, dead space, and a link that reloads the same numbers. A phone app that saves protocols, reminders, and dose logs is a different product. PepCalc only calculates.
Does PepCalc recommend a dose?
No. It applies the formula to numbers you type. It does not decide whether a peptide, amount, schedule, or injection site is appropriate.
Can I share a result?
There is no share button. Copy keeps the result text, and Log stores the same numbers in the history on this browser.
Does PepCalc store what I enter?
There is no account. A history log stays in this browser only. Clearing site data removes the log.
Limits
What is dead space?
A little liquid stays in the needle and hub. PepCalc can add that volume to the draw, or subtract it when solving for water, so what leaves the syringe is closer to the dose you typed. A common allowance is about 0.05 mL. Measure your own syringe if you use it.
Which syringe does this assume?
U-100 insulin syringes: 100 units equal 1 mL. A 0.3 mL barrel is 30 units, 0.5 mL is 50, and 1 mL is 100. The scale is the same. PepCalc warns you if the draw is larger than the barrel.
Is this medical advice?
No. Confirm the label, the diluent, and the dose with a licensed clinician or pharmacist before you mix or measure anything.
Topics
Math pages only. Grouped by subject, not by a suggested use.